[Bug 1982326] Re: race between exit() and pthread_exit() with static linking

[lotuspsychje]

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https://bugs.launchpad.net/bugs/1982326

Title:
  race between exit() and pthread_exit() with static linking

Status in glibc package in Ubuntu:
  New

Bug description:
  When statically linking a C multi-threaded application, there is a race between pthread_exit() and exit() which may cause pthread_exit() to abort the program.
  It appears the issue is due to the forced unwind executed by pthread_exit() failing because _Unwind_Find_FDE() returns NULL. Apparently, _Unwind_Find_FDE() returns NULL after __deregister_frame_info_bases() is called as part of the exit handlers invoked by exit().
  The issue is easily reproducible (in my machine it occurs approximately in 1 out of 3 runs) when running the attached sample program under strace.
  Steps to reproduce:
  - build the attached source with `gcc thread_test.c -lpthread -static -o thread_test`
  - run with `strace -f ./thread_test`

  Example output:
  ```
  <snip>
  [pid 28302] +++ killed by SIGABRT (core dumped) +++
  +++ killed by SIGABRT (core dumped) +++
  Aborted (core dumped)
  ```

  If the commented code in the sample source is uncommented, we can
  confirm that _Unwind_Find_FDE() sometimes returns NULL.

  Ubuntu 18.04.6 LTS
  Package: libc6 2.27-3ubuntu1.6
  Source package: https://launchpad.net/ubuntu/+source/glibc/2.27-3ubuntu1.6

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